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<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
    <title>Three.js - Custom BufferGeometry - Cube</title>
    <style>
    html, body {
        height: 100%;
        margin: 0;
    }
    #c {
        width: 100%;
        height: 100%;
        display: block;
    }
    </style>
  </head>
  <body>
    <canvas id="c"></canvas>
  </body>
<!-- Import maps polyfill -->
<!-- Remove this when import maps will be widely supported -->
<script async src="https://unpkg.com/es-module-shims@1.3.6/dist/es-module-shims.js"></script>

<script type="importmap">
{
  "imports": {
    "three": "../../build/three.module.js"
  }
}
</script>

<script type="module">
import * as THREE from 'three';

function main() {
  const canvas = document.querySelector('#c');
  const renderer = new THREE.WebGLRenderer({canvas});

  const fov = 75;
  const aspect = 2;  // the canvas default
  const near = 0.1;
  const far = 100;
  const camera = new THREE.PerspectiveCamera(fov, aspect, near, far);
  camera.position.z = 5;

  const scene = new THREE.Scene();

  {
    const color = 0xFFFFFF;
    const intensity = 1;
    const light = new THREE.DirectionalLight(color, intensity);
    light.position.set(-1, 2, 4);
    scene.add(light);
  }

  // NOT A GOOD EXAMPLE OF HOW TO MAKE A CUBE!
  // Only trying to make it clear most vertices are unique
  const vertices = [
    // front
    { pos: [-1, -1,  1], norm: [ 0,  0,  1], uv: [0, 0], },
    { pos: [ 1, -1,  1], norm: [ 0,  0,  1], uv: [1, 0], },
    { pos: [-1,  1,  1], norm: [ 0,  0,  1], uv: [0, 1], },

    { pos: [-1,  1,  1], norm: [ 0,  0,  1], uv: [0, 1], },
    { pos: [ 1, -1,  1], norm: [ 0,  0,  1], uv: [1, 0], },
    { pos: [ 1,  1,  1], norm: [ 0,  0,  1], uv: [1, 1], },
    // right
    { pos: [ 1, -1,  1], norm: [ 1,  0,  0], uv: [0, 0], },
    { pos: [ 1, -1, -1], norm: [ 1,  0,  0], uv: [1, 0], },
    { pos: [ 1,  1,  1], norm: [ 1,  0,  0], uv: [0, 1], },

    { pos: [ 1,  1,  1], norm: [ 1,  0,  0], uv: [0, 1], },
    { pos: [ 1, -1, -1], norm: [ 1,  0,  0], uv: [1, 0], },
    { pos: [ 1,  1, -1], norm: [ 1,  0,  0], uv: [1, 1], },
    // back
    { pos: [ 1, -1, -1], norm: [ 0,  0, -1], uv: [0, 0], },
    { pos: [-1, -1, -1], norm: [ 0,  0, -1], uv: [1, 0], },
    { pos: [ 1,  1, -1], norm: [ 0,  0, -1], uv: [0, 1], },

    { pos: [ 1,  1, -1], norm: [ 0,  0, -1], uv: [0, 1], },
    { pos: [-1, -1, -1], norm: [ 0,  0, -1], uv: [1, 0], },
    { pos: [-1,  1, -1], norm: [ 0,  0, -1], uv: [1, 1], },
    // left
    { pos: [-1, -1, -1], norm: [-1,  0,  0], uv: [0, 0], },
    { pos: [-1, -1,  1], norm: [-1,  0,  0], uv: [1, 0], },
    { pos: [-1,  1, -1], norm: [-1,  0,  0], uv: [0, 1], },

    { pos: [-1,  1, -1], norm: [-1,  0,  0], uv: [0, 1], },
    { pos: [-1, -1,  1], norm: [-1,  0,  0], uv: [1, 0], },
    { pos: [-1,  1,  1], norm: [-1,  0,  0], uv: [1, 1], },
    // top
    { pos: [ 1,  1, -1], norm: [ 0,  1,  0], uv: [0, 0], },
    { pos: [-1,  1, -1], norm: [ 0,  1,  0], uv: [1, 0], },
    { pos: [ 1,  1,  1], norm: [ 0,  1,  0], uv: [0, 1], },

    { pos: [ 1,  1,  1], norm: [ 0,  1,  0], uv: [0, 1], },
    { pos: [-1,  1, -1], norm: [ 0,  1,  0], uv: [1, 0], },
    { pos: [-1,  1,  1], norm: [ 0,  1,  0], uv: [1, 1], },
    // bottom
    { pos: [ 1, -1,  1], norm: [ 0, -1,  0], uv: [0, 0], },
    { pos: [-1, -1,  1], norm: [ 0, -1,  0], uv: [1, 0], },
    { pos: [ 1, -1, -1], norm: [ 0, -1,  0], uv: [0, 1], },

    { pos: [ 1, -1, -1], norm: [ 0, -1,  0], uv: [0, 1], },
    { pos: [-1, -1,  1], norm: [ 0, -1,  0], uv: [1, 0], },
    { pos: [-1, -1, -1], norm: [ 0, -1,  0], uv: [1, 1], },
  ];
  const positions = [];
  const normals = [];
  const uvs = [];
  for (const vertex of vertices) {
    positions.push(...vertex.pos);
    normals.push(...vertex.norm);
    uvs.push(...vertex.uv);
  }

  const geometry = new THREE.BufferGeometry();
  const positionNumComponents = 3;
  const normalNumComponents = 3;
  const uvNumComponents = 2;
  geometry.setAttribute(
      'position',
      new THREE.BufferAttribute(new Float32Array(positions), positionNumComponents));
  geometry.setAttribute(
      'normal',
      new THREE.BufferAttribute(new Float32Array(normals), normalNumComponents));
  geometry.setAttribute(
      'uv',
      new THREE.BufferAttribute(new Float32Array(uvs), uvNumComponents));

  const loader = new THREE.TextureLoader();
  const texture = loader.load('resources/images/star.png');

  function makeInstance(geometry, color, x) {
    const material = new THREE.MeshPhongMaterial({color, map: texture});

    const cube = new THREE.Mesh(geometry, material);
    scene.add(cube);

    cube.position.x = x;
    return cube;
  }

  const cubes = [
    makeInstance(geometry, 0x88FF88,  0),
    makeInstance(geometry, 0x8888FF, -4),
    makeInstance(geometry, 0xFF8888,  4),
  ];

  function resizeRendererToDisplaySize(renderer) {
    const canvas = renderer.domElement;
    const width = canvas.clientWidth;
    const height = canvas.clientHeight;
    const needResize = canvas.width !== width || canvas.height !== height;
    if (needResize) {
      renderer.setSize(width, height, false);
    }
    return needResize;
  }

  function render(time) {
    time *= 0.001;

    if (resizeRendererToDisplaySize(renderer)) {
      const canvas = renderer.domElement;
      camera.aspect = canvas.clientWidth / canvas.clientHeight;
      camera.updateProjectionMatrix();
    }

    cubes.forEach((cube, ndx) => {
      const speed = 1 + ndx * .1;
      const rot = time * speed;
      cube.rotation.x = rot;
      cube.rotation.y = rot;
    });

    renderer.render(scene, camera);

    requestAnimationFrame(render);
  }

  requestAnimationFrame(render);
}

main();
</script>
</html>

